Before Minnesota United plays the first playoff game in its MLS history in two weeks, it will play another Sunday at Seattle.

Win and the Loons clinch second place in the Western Conference and a home playoff game that would set up another one if they win again.

With a tie against the Sounders, United can still finish second if L.A. Galaxy loses at Houston. Lose and it still secures a first-round home game if Real Salt Lake loses at Vancouver.

They'll finish fifth and hit the playoff road if they lose and both L.A. Galaxy and Real Salt Lake win.

"It kind of starts this weekend," United veteran defender Ike Opara said. "It's pretty much a playoff game before the playoffs. We're getting a good taste of it before the real thing."

The Sounders will open CenturyLink Field's second deck with 40,000 or more fans possible.

"If you don't want to play in big stadiums with full crowds and everything on the line, you shouldn't be playing," United coach Adrian Heath said. "You should be playing somewhere else."

Seattle now has made the playoff 11 consecutive seasons and won the 2016 MLS Cup. The first 10 were with a squad including Ozzie Alonso, who returns Sunday with United.

CONCACAF in sight

United still could be one of four MLS teams in the prestigious CONCACAF Champions League starting in February.

Atlanta United, NYCFC and LAFC already have qualified. If one of those three also wins the MLS Cup, another team qualifies. If Philadelphia doesn't defeat NYCFC and United defeats Seattle, United will compete in the 16-team tournament, which features top teams from North and Central America and the Caribbean.

Scoreboard watching

All 12 MLS games Sunday start at 3 p.m. Central to maintain the integrity of each game. That doesn't mean Heath and his staff won't monitor the progress of L.A. Galaxy-Houston and Real Salt Lake-Vancouver, as both matches could have bearing on his team's place in the final standings.

"You do have to look because sometimes a draw would be enough," Heath said.

Heath could change his team's formation and call upon defensive-minded Hassani Dotson and Lawrence Olum to play for that draw. He also must decide if veteran striker Angelo Rodriguez, who provided a second-half spark Sunday against LAFC, or Mason Toye starts up top.

"We have to make sure we make the right decision at the weekend," Heath said Thursday, "and I don't know what that's going to be yet."